Megascops asio (*)
Megascops asio (Linnaeus, 1758)
Systema Naturae ed.10 p.92
The Eastern Screech Owl or Eastern Screech-Owl (Megascops asio) is a small owl that is relatively common in Eastern North America.
Adults range from 16 to 25 cm (6.3-10 in) in length and weigh 121-244 grams (4.3-8.6 oz). They have either rusty or dark gray intricately patterned plumage with streaking on the underparts. Mid-sized by screech-owl standards, these birds are stocky, short-tailed and broad-winged. They have a large round head with prominent ear tufts, yellow eyes and a yellowish bill. Rusty birds are more common in the southern parts of the range; pairings of the two color variants do occur. A pale gray variation also exists in western Canada and the north-central United States. The color variations are referred to as "red-phase" and "gray-phase" by bird watchers and ornithologists.
Their breeding habitat is deciduous or mixed woods in eastern North America. Usually solitary, they nest in a tree cavity, either natural or excavated by a woodpecker; they will also use nesting boxes. Eggs are laid every two days and incubation begins after laying of the first egg. The incubation period is about 26 days and the fledging period about 31 days. Females do most of the incubating but males will assist. The male provides most of the food while the female broods the young, and will stockpile food during early stages. Eastern Screech Owls are single brooded, but may re-nest if the first clutch is lost. When the young are small the female tears the food up for them.
They are strictly nocturnal, roosting during the day in cavities or next to tree trunks. They are quite common, and can often be found in residential areas. Though they generally go unnoticed, these owls are frequently heard calling at night, especially during their spring breeding season. Despite their name, this owl (nor most "screech-owls") doesn't truly screech. The Eastern Screech-Owl's call is a haunting tremolo with a descending, whinny-like quality.
While Eastern Screech Owls have lived over 20 years in captivity, wild birds seldom if ever live that long. Mortality rates of young and nestling owls may be as high as 70% (usually significantly less in adult screech owls). Many loses are due to predation. Common predators at screech owl nests including mink, weasels, raccoons, skunks, snakes, crows, and blue jays. Adults have fewer predators but larger species of owl do take them, since they have similar periods of activity. Larger owls known to have predated Eastern Screech Owls have included Great Horned Owls, Barred Owls, Long-eared Owls, Great Gray Owls, Short-eared Owls amd Snowy Owls.
Eastern Screech Owls inhabit open mixed woodlands, deciduous forests, parklands, wooded suburban areas, riparian woods along streams and wetlands (especially in drier areas), mature orchards, and woodlands near marshes, meadows, and fields. They try to avoid areas known to have regular activity of larger owls, especially Great Horned Owls. These owls roost mainly in natural cavities in large trees, including cavities open to the sky during dry weather. In suburban and rural areas they may roost behind loose boards on buildings, boxcars, or water tanks. They will also roost in dense foliage of trees, usually on a branch next to the trunk, or in dense scrubby brush.
Like most predators, Eastern Screech-Owls are opportunistic hunters. They hunt from dusk to dawn, with most hunting being done during the first four hours of darkness. A combination of sharp hearing and vision is used for prey location. These owls hunt mainly from perches, occasionally hovering to catch prey. This owl mainly hunts in open woodlands, along the edges of open fields or wetlands, or makes short forays into open fields. When prey is spotted, the owl dives quickly and seizes it in its talons. Small prey will usually be swallowed whole on the spot, while larger prey is carried in the bill to a perch and then torn into pieces. An Eastern Screech Owl will tend to frequent areas in its home range where it hunted successfully on previous nights.
For the better part of the year, large insects are favored in their diet, with invertebrates often comprising more than half of the owls' diet. Some regularly eaten insects include beetles, moths, crickets, grasshoppers and cicadas. Also taken are crayfish, snails, spiders, earthworms, scorpions, and centipedes. Small mammals, ranging in size from shrews to rabbits, are regular prey and often become the owl's primary prey during winter. Small rodents such as microtine rodents and mice comprise about 67% of mammals taken, although rodents of a similar weight to the owl, such as rats and squirrels are taken. Small birds such as chickadees, sparrows and warblers are the most common avian prey and such species are normally caught directly off of their nocturnal perches or during nocturnal migration. However, much larger avian prey is sometimes caught, including rock pigeons, northern bobwhite and even ruffed grouse (which are heavier than the screech owls). Irregularly, small fish, small snakes, lizards, baby soft-shelled turtles, small frogs, toads, and salamanders are also preyed upon. They have even been observed hunting for fish at fishing holes made by people or cracks in ice at bodies of water during winter.
This species is infected by several parasites including Plasmodium elongatum, Plasmodium forresteri and Plasmodium gundersi.
In popular culture
The 1992 comedy My Cousin Vinny starring Joe Pesci and Marisa Tomei has a scene with a Screech Owl. During the scene, the owl disturbs the main characters' sleep with its call. The bird's call is not realistically portrayed in the movie; the movie audio has the call as a loud, abrasive "screech".
1. ^ Sibley, David (2003). The Sibley Field Guide to Birds of Eastern North America. New York: Alfred A. Knopf. p. 225. ISBN 0-679-45120-X.
* BirdLife International (2004). Megascops asio. 2006. IUCN Red List of Threatened Species. IUCN 2006. www.iucnredlist.org. Retrieved on 11 May 2006. Database entry includes justification for why this species is of least concern
Source: Wikipedia, Wikispecies: All text is available under the terms of the GNU Free Documentation License